Stratified sampling (1 Viewer)

[random-nobody23]

What is it? How do you work it out in terms of this question:

Ms Wigginson decided to survey a sample of 10% of the students at her school.

The student enrolment is
year 7- 225 students
year 8- 232 students
year 9- 233 students
year 10- 230
year 11- 150
year 12- 130
TOTAL- 1200

she surveyed the same number from each year
How would the numbers of students surveyed in year 10 and 11 have changed if Ms Wigginson had chosen to use a stratified sample based on year groups?

So i got 10% of the school is 120 students, so thats 20 from each year...
so yeah, can someone help please
thanks in advance!

 

[radioheaded]

stratified sample would be

(230÷1200) X 120
= approx 23 Year 10 students

(150÷1200) X 120
= approx 15 Year 11 students

therefore fewer year 11's, more year 10's

(got this from worked answers in a book

hope this helped

 

[Heiday]

stratified sample would be

(230÷1200) X 120
= approx 23 Year 10 students

(150÷1200) X 120
= approx 15 Year 11 students

therefore fewer year 11's, more year 10's

(got this from worked answers in a book

hope this helped

why x 120? shouldnt it be 100?

 

[michael1990]

why x 120? shouldnt it be 100?

10% of the school is 120 students.